Fuse for aerial drop-bombs



March s, 1938. A. G. HAYDEN 2,110,552

FU E FOR AERIAL DROP BOMBS Filed Dec. 21, 1936 Patented Mar. 1938 I V UNITED STATES PATENT OFFICE v I I I FUSE roe minor-norms I Arthur G. .Hayden,\Qakland, Calif. Application December 21, 1936, Serial No..116,876

Claims.

This invention relates to timing fusesfor aerial bombs by means of which the interval of time between the launching of the bomb, from an aircraft or other carrier, and the explosion there- 5 of, may be regulated.

It is an object of the invention to provide a fuse for aerial bombs which operates by changes in atmospheric pressure.

Another object of the invention is to provide a fuse which may be set by the bomber, to explode the bomb at a certain altitude, without necessitating complex calculations on the part of the bomber before setting the fuse. V

A further object of the invention is to provide a fuse which may be set to function either to explode the bomb at a predetermined altitude, or by shock caused by the bomb striking an object.

Still another object of the invention is to 29 provide in a timing head for an aerial bomb,

wherein the fuse for exploding the bomb is actuated by changes in atmospheric pressure, means for prevention, due to the flight of the bomb, the creation of pressures difiering from the pressure of the atmosphere through which the bomb is passing on the fuse actuating mechanism.

The invention' possesses other objects and valuable features, some of which, together with the foregoing, will be specifically set forth in the specification hereunto annexed. It is to be understood that the invention is not to be limited to the particular species thereof shown and described as various other embodiments thereof 'may be employed within the scope of the appended claims.

Referring to the drawing:

Figure 1 is a vertical sectional view, partly in elevation, of a bomb timing head including the fuse of my invention.

Figure 2 is a cross-sectional view of the timing head. The plane of section is indicated by the line 2--2 of Figure 1.

Figure 3 is a cross-sectional view of the head.

The plane in which this view is taken is indicated by the line 33 of Figure 1. I

Figure 4 is a cross-sectional view of the adjusting screw for the bellows. The plane of section is indicated by the line 4-4 of Figure 1.

In detail, the fuse of my invention is mounted in a specially constructed head comprising a lower housing 6, a cover I, and a cap 8 whose peripheries are each shaped to provide the bullet-shaped structure shown in Figure 1.

The housing 6 is provided at its lower end with, a threaded nipple 9, by means of which the head may be attached to the body of the bomb, and is hollowed out to provide a chamber II. Midway between the ends of the housing is a partition I2 from which depends a hub 13 5 which is concentric with the axis of the housing.

The cover I is provided with a downwardly extending nipple M, which seats in the upper open end of the housing 6 and is secured there- 10 in by setscrews l5, and with a central recess ll closed at its upper end by a wall I8 having an aperture l9 therethrough. In the bottom of the recess H is a hub 2i having a square bore 22 therein.

The cap 8 has therein a central hub 23 provided with a bore 24 which receives a shaft 28 secured to the cap by a setscrew Z'l. The lower end of the shaft 26 is provided with a bore 28 in which is secured, by the pin 29, the shank 2o 31 of the adjusting screw 32, which passes throug the aperture N.

Disposed in the aperture ll of the cover I is an axially resilient evacuated metallic bellows 33 having at its upper end a square hub 25 34 which slidably engages in the bore 22 and a threaded recess located centrally of the hub in which the adjusting screw 32 is engaged. The lower end of the bellows is provided with a centrally apertured yoke 36' having depending there- 30 from a stud 31 which slidably engages in an aperture 38 formed axially of the hub I3. 'The bellows, being evacuated in the manner of the bellows of the conventional barometer, will be aifected by changes in atmospheric pressure. 35 Thus at or near sea level, the bellows will be contracted axially and as higher altitudes are reached the lessening of the pressure of the atmosphere will allow the bellows to axially expand, thereby causing the yoke 36 to move up- 40 ward or downward as the bellows is affected.

Pivotally mounted on a pin secured in a bracket 39, formed on the wall l2 of the housing 6, is a lever one arm 4| of which enters the aperture of the yoke 36 and the other arm 42 of 45 which extends outwardly from the bracket over the surface of the wall. The arm 42 is provided with a transverse rod 43 to the opposite ends of which are secured the ends of a pair of coil springs 44 whose opposite ends are at- 50 tached to spaced lugs 46 rising from the wall I2. It will be seen, in Figure 1, that the longitudinal axis of each spring lies, when the lever is positioned as shown in the figure, angularly with respect to the lever pivot pin and that the 55 position of the rod 43 of the lever arm 42 is such that, as the lever is moved, the axis of each spring .will move across the pivotal axis of the lever. Thus a toggle action is provided by the positioning of the springs, the latter tending to maintain the lever in one extreme position when the parts are disposed as shown in Figure 1, and causing the lever, when movement thereof moves the axes of the springs downwardly past the lever pivot, to snap the lever into its extreme downward position wherein the arm 42 will be lowermost and the arm 4| will be elevated. It will be seen therefore that, since the arm 4! is engaged with the yoke 36, axial contraction or expansion of the bellows, between certain limits, will cause the toggle lever to snap from one extreme position to the other.

Means is provided for igniting an explosive charge or primer for the bomb when the lever snaps into one of its extreme positions. Secured, in a block of insulating material 41, in the wall 12, is a contact 48, upon which the distal end of the arm 42 is adapted to rest when this arm is in its lower position, and connected to the contact is a conductor 49 which passes upwardly through an aperture 5|, formed in the wall I2, and is secured to a contact clip 52 mounted on an insulating block 53 carried on the inner side of the wall of the housing 6. The cover I is provided with a plurality of spaced recesses 54 each containing a dry battery 56 and the terminal of one of these batteries contacts the clip 52. Each of the batteries is connected in series with its neighbor, as is shown in Figure 2, a plurality of jumpers 57 each being insulated from the cover by blocks 58, being provided for conducting the current of one cell to the other. The final cell of the series is contacted by a clip 59, mounted on an insulating block 6| secured to the inner surface of the housing side wall, having a curved finger 52 extending downwardly therefrom. Also mounted on the insulating block 6| is a clip 63 having an upwardly curved finger 64 similar to the finger 62 and positioned directly below the latter. A conductor 66 connects the clip 63 with the insulated terminal 61 of an igniter comprising a metallic plug 68 which is screwed into the upper end of a bore 69 formed in the housing hub 13. Into the lower end of the bore is screwed an apertured plug H which provides in the bore a chamber 12 into which explosive material 13 is packed. The lower end of the terminal 61 is joined with a grounded terminal 14 mounted in the plug 68 by a fusible wire 16. I

The fingers 62 and 64 are normally held apart by a safety pin 11 of insulating material which is slidably mounted in a sleeve 18 projecting through the side wall of the housing into the chamber H and the pointed end 19 of the pin overlies the lever arm 41! and prevents the latter from moving. When the safety pin is withdrawn, the lever arm is freed and the fingers 62 and 64 move into contact with each other. It will thus -be seen that the electric circuit is completed from the contact 48, through the conductor 49, through the series of batteries 56, the contacting fingers 62 and 64, the conductor 66, the igniter, and the housing, back to the lever arm 42 which overlies the contact 48. If the timing head were now screwed on to the main body of the bomb and the toggle switch was tripped to move the arm 42 into engagement with the contact 48, the flow of current in the circuit above described would melt the fuse l6 and ignite the priming charge 13 thereby exploding the bomb. It will be seen that as long as the safety pin is in position to hold the lever against movement and the fingers 62 and 64 separated ignition of the priming charge cannot take place. Even though the pin is moved outwardly to free the lever, the charge cannot be ignited since the open contact between the fingers precludes the possibility of current flowing from the batteries through the circuit. Thus, in order to condition the bomb for firing the safety pin 11 must be completely withdrawn.

The timing head may be set by the bomber so that the explosion of the bomb will take place at any predetermined altitude below the craft from which it is dropped. The bellows for each individual timing head is calibrated at ground level so that its degree of contraction and consequently the position of the toggle switch with relation to its dead center is definitely known. Thus, when the ship carrying the bomb is flying at an altitude of 10,000 feet, for example, and a bomb is to be released to explode in the vicinity of an enemy ship flying at 5,000 feet, the bomber knowing his present altitude and the amount that the bellows has expanded since leaving the ground need only rotate the cap 8 to draw the bellows upwardly to move the lever to such an angle with respect to its dead center that the increase in pressure which occurs after the bomb has dropped through 5,000 feet will be sufficient to contract the bellows and swing the toggle switch over dead center to close the electric circuit between the contact 48 and the arm 42. To facilitate handling of the cap 8 the latter is provided with a knurled finger grip BI, and to enable the bomber to ascertain the amount that the bellows is being moved axially, the edge of the cap is provided with a suitable reference scale 82 whose graduatlons are adapted to register with a fixed index 83 on the cover I.

To preclude the possibility of excess air pressure building up in the chamber surrounding the bellows, due to the flight of the bomb through the air, means is provided for maintaining the pressure in the chamber constantly equal to the atmospheric pressure through which the bomb is passing. This is done by providing the cap 8 with a plurality of inlet apertures 84 through which air may enter the chamber, apertures 86 and 81 in the walls l8 and I2 respectively of the cover and housing through which the air entering the chamber through the apertures 84 may flow and apertures 88 entering the chamber through the side walls of the lower portion of the housing through which the air may flow from the chamher. It will be seen that since the combined areas of the apertures 84 and 88 are equal as much air will be exhausted from the chamber as enters it through the inlet apertures with the result that the pressure in the chamber is maintained equal to that of the outer atmosphere, therefore no abnormal pressure will exist in the chamber which might adversely affect the operation of the timing mechanism.

It will be seen that the timing head is also capable of being used to explode the bomb upon impact with a body. This operation may be obtained by moving the bellows and the yoke downwardly, as viewed in Figure 1, beyond the point where the atmospheric pressure at the altitude at which the objective is located will not compress the bellows suflficiently to trip the toggle switch. The safety pin is now withdrawn and the bomb is launched. When the head of the bomb strikes the objective the bomb will of course be checked and the momentum of the free end of the bellows and its attached yoke and pin 31 will be sufiicient to flip the arm 4| of the toggle switch toward the nose of the bomb and thereby close the contacts 48 and 42.

The timing head of my invention differs widely from those using clockwork to actuate the fuse.

A bomb equipped with the present timing head may be repeatedly reset for firing at different targets as compared with the clockwork bombs which may not be reset once the clockwork has been started. In addition the calculation of time required for the bomb to follow a trajectory between its point of launching and the objective is unnecessary with my timing head since it operates entirely on changes of altitude without any consideration of time.

I claim:

1. A fuse for an aerial bomb comprising an electric igniter, an electrical circuit, including a source of current,'connected with said igniter, a normally open switch in said circuit, a hollow evacuated member operatively connected with said switch, said member being contractible along a path of movement in response to differences in external and internal pressures to move said switch along said path between extreme open and closed positions, and means for shifting said member along said path to position said switch at a selected position between the extreme open and closed positions thereof.

2. A fuse for an aerial bomb comprising a housing having a chamber therein, a threaded shaft journaled in and extending from said housing, a dial secured to said shaftfor manually rotating said shaft, an element expansible and contractible in accordance with changes of atmospherie pressure disposed in said chamber, said element being threadedly engaged at one end thereof with the threaded portion of said rotatable shaft whereby, upon rotation of said shaft, said element will be moved bodily, an electric igniter and a source of electric current in said housing, an electrical circuit connected with said igniter and said current source, and a switch in said circuit and connected tobe actuated by movement of said element.

3. A fuse for an aerial bomb comprising a housing having a chamber therein, a threaded shaft journaled in and extending fromv said housing, a dial secured to said shaft for manually rotating said shaft, an element expansible and contractible in accordance with changes of atmospheric pressure disposed in said chamber, said journaled in and extending from said housing, a dial secured to said shaft for manually rotating said shaft, an element expansible and contractible in accordance with changes of atmospheric pressure disposed in said chamber, said element being threadedly engaged at one end thereof with the threaded portion of said rotatable shaft whereby, upon rotation of said shaft, said element will be moved bodily, an electric igniter and a source of electric current in said housing, an electrical circuit connected with said igniter and said current source, a switch in said circuit and connected to be actuated by movement of said element, means for holding said element against movement, and means for venting said chamber to the atmosphere.

5. A fuse for an aerial bomb comprising a housing having a chamber therein, a threaded shaft journaled in and extending from said housing, a dial secured to said shaft for manually rotating said shaft, an element expansible and contractible in accordance with changes of atmospheric pressure disposed in said chamber, said element being threadedly engaged at one end thereof with the threaded portion of said rotatable shaft whereby, upon rotation of said shaft, said element will be moved bodily axially of said shaft, an electric igniter and a source of electric current in said housing, an electrical circuit connected with said igniter and said current source, a switch for establishing and interrupting said electrical circuit, said switch comprising an insulated contact connected in said circuit, a lever pivotally mounted in said housing for movement in a path axially of said shaft, said lever having an arm movable to engage said contact and a second arm in engagement and movable with said element, and means for accelerating the movement of said lever during a portion of its movement along said path.

ARTHUR G. HAYDEN. 

